A computational fluid dynamics software package was used to study heat tran
sfer from spherical particles of different sizes and under different heat-t
ransfer conditions. It was shown that although the Ranz-Marshall and other
similar correlations are valid in the case where particles do not interact,
this is not true for densely packed systems such as those that we find in
reactors commonly used in olefin polymerization. It,, ns also demonstrated
that convection is in fact not the only means of removing heat from small h
ighly? active particles. Conductive heat transfer between large and small p
articles present in the same reactor appears to help alleviate problems of
overheating and explain why earlier models of heat transfer in olefin polym
erization overpredict the temperature rise during early stages of polymeriz
ation.